MULTRITROPHIC INTERACTIONS INVOLVING INVASIVE INSECT PESTS OF TREES

The overall goal of this project is to develop approaches to mitigate the negative consequences of non-native, invasive insect pests of trees in the urban/rural landscape, which threaten the health of forest and ornamental trees, by using knowledge gained from investigations of insect-plant-natural enemy interactions in several systems. European gypsy moth (Lymantria dispar), is a formidable pest in the United States and the larval form is a major cause of defoliation of deciduous trees. Despite significant control efforts, the gypsy moth has persisted and continues to expand its range. A virus commonly found in the field that infects the gypsy moth is mass-produced by the USDA as Gypcheck for field applications to control gypsy moth outbreaks, but production is very labor intensive and requires fairly high viral doses to achieve adequate control. The goal of this objective is to increase our understanding of interactions between the gypsy moth, its host plants, and the virus to identify potential genetic targets for improving efficacy of the virus against the gypsy moth. The Asian longhorned beetle (ALB; Anoplophora glabripennis) is an exotic insect that attacks and kills a wide variety of hardwood tree species. Development of a greater range of management options is of the utmost importance, especially given that effective direct control measures are limited almost exclusively to tree removal and tree injection with insecticides. There is potential for developing management tactics for ALB by manipulating the insect's gut physiology, perhaps by altering the gut microbial community. Using a species of poplar that is resistant to ALB compared with a susceptible poplar species, changes in the beetle gut microbial community structure and functions will be studied using molecular techniques to determine if the plant effects on the gut symbionts or on the beetle itself. Hemlock woolly adelgid (HWA) currently infests nearly one-half of the native range of hemlock in the East. Also as populations of HWA increase, hemlock mortality increases, shifting forest composition towards deciduous trees that are less able to maintain cool forest and stream conditions for the diversity of species that require these types of habitats. Although two predatory beetles have been established for biological control of HWA, they are spreading slowly. Scymnus camptodromus, a tiny lady beetle native to China, was recently brought to the U.S. It has a high likelihood of establishing in the U.S. as a major natural enemy of HWA. The outcome of this project will be development of a biological control program for HWA using this predatory beetle. The approach will be to develop methods to mass rear the predator and evaluate its effectiveness for control of HWA.